Hydraulic booster



June 8, 1948. J. D. BUCHANAN HYDRAULIC BOOSTER 6 Sheets-Sheet 1 Filed Nov. 5, 1945 I INVENTOR: 1/, D 15 UCHANA 1v.

ATTOPA/EK v June 8, 1948. J. D. BUCHANAN 2,442,916

HYDRAULIC BOOSTER Filed Nov. 5, 1945 6 Sheets-Sheet 2 6 T INVENTOR: z/T D. BUCHANAN.

A TTOENE 1 6 Sheets-Sheet 3 HYDRAULIC BOOSTER J. D. BUCHANAN "I/IIIIIIIII]. 7/ III/III INVENTOR: J: 0.5UCHA/VA/V.

ATTOPNEK June 8, 1948;

Filed Nov. 5, 1945 June 8, 1948. J. D. BUCHANAN HYDRAULIC BOOSTER 6 Sheets-Sheet 4 Filed Nov. 5, 1945 5 3 6 3 7 4; 4 3L]: 3!; a w x i 9 9 .2 w 3 W 0 w 2 a 4 I a .9. a m

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I INVENTOR: J. D. BUCHANAN. BY

J. D. BUCHANAN HYDRAULIC BOOSTER 6 Sheets-Sheet 5 Filed Nov. 5, 1945' INVENTOR: J .0; BUCHANAN.

,4 Woe/1H4 9 1948- J. D. BUCHANAN 9 HYDRAULIC BOOSTER Filed Nov. 5, 1945 6 Sheets-Sheet 6 1 N VEN TOR.

Patented June 8, 1948 RAULIC oos'run J. D'jlsiicliananffiurbarik; can;

ApplicationNovernber 5, 1945, Serial NOTGZBJYB The invention relates to an hydraulic booster and more particularly to hydraulic apparatus employing a differential pumppiston having a com"- paratively large area acted on by a low pressure source, the piston having" a, comparatively small piston area employed to'raiseithe' pressure of the sarnelsource' or another source of fiuidby an amount approximating" tliratio'of the two areas of the piston. The pump piston is double acting boosting the pressure at each stroke. While boosters employing double acting' pump'p'istons have been proposed'heretofore, the present invention is distinguished'thereirom unimproved arrangements of an hydraulic nature for controlling the pumping. action; for the production of a high pressure fluid output" of substantially constant ve1ocity,-.assuinin'g the working pressureis substantially constant. The invention further relates to animproved booster construction to facilitate its manufacture;

The present invention relates toa booster havirig two such pump'pisto'n's which are operated with overlapping strokes whereby each piston is pumping at a time when the "other p'is'ton'isl at the end of its stroke, each piston'being ope'rated'by a reversing valve, and each pump pistoii'actihg as a pilot valve for the rever'singvalvefor the other pumppi'ston. The pump pistonsiarethus' controlled'by reversingvalves which are operated by fluid pressure under control of. the pump. pistons.

Both pump pistons, their reversing .v'alvesa'nd the..working and control passages therefor are preferably arranged in a unitary structure." To

facilitate the manufacture of the pump piston, the. piston. member is providediwith a'piston'. at: each end thereof and'withanintermediate portion of reducecl dia'meter', whereby ittis possible to use a cylinder liner of. uniform diameter for thepis ton,..a.,purnping. space. being provided inwardly of each piston by providing thecylinder. liner with a packing glandgfor thereduced central'iportion of the pisto'nmember, the space between the pack ing land and each inner end flthe.plStOIl serv ing as a pumping space, one, of which is on a suction strohe'when the other is on a compression stroke. t

,The invention further provides a compact unit in which areassembled the two double pump pistonstwo reversing valves. and eight check valves, two-for each pump portion of each piston.

For further details, of the invention reference Figs. 4 to '7, inclusive, are schematic simplified s was; (01. 103-52) diagrams illustrating; the sequence. of. operation of the pump pistons and-theirv reversingvalves.

Figs. ,8, .9; .10 and 11' areverticalsectional views looking in'thedirection of the arrows-on the lines of the correspondinginumbers'in Fig.'3.

Fig. 12 is a vertical sectional view on line l2..-i 2 of Fig. lOlooking in the; direction of the arrows. Fig. 13 is a horizontal sectional viewflonlline l3 -I3 of Fig. 12looking-in-the directionof the arrows. V,

Referring in; detail :to the-drawings; the booster 5 comprises difierentia-l pumping mechanism later described which may .be operated bylow-pressure fluid delivered for example by ;pump 2 ;from a s mp 3 9 e mp e-.1. T e 1 w p su e; fl i in pipe 4 is hereafter referred toes-the workingpressure 0 Wwkine-iluidand e a 1ne t pumpingmechanism in booster I it is'returned by pipe .5 to the sump fi Fluidumder pressure,

either. from pump 2 or fron some other source, is

supplied to the highepressure suction or inlet 6 and this fluid is delivered at' higher pressure to the high p s e'eu letl=, .1,

Referring to Figefiwhichis'a top; plan View of the booster l in Fig.1, theboioster comprises a casing 8 having aniinlet for the low pressure inlet 4,Yan outlet: [if for thelow pressure outlet 5. for the working fluid, an outlet ll tor the high pres: sure outlet- .aifid directly therebelovv arr-inlet, not shown in Fig. :3 (butindicated-at23"in;Fig. 9), for the high pressureinletfi in Fig. 1 'l he. casing. 8 has twepata pr um cylinders l2 and. it

closed at their opDQsite ends by cylinder heads' such as indicatedat"l?lf. .Ahove the pump cylinders 12,1!3ai1d parallel thereto, are' reversing valve cylinders-15.1.5, each closed at its opposite endsby cylinder'he'ads' suchas indicated at i! in Fig. 3 and at 14 and. in Fig. 8. .Each of the pumpcylinders 121 131155 a; double acting, difier- *ential' pump piston, the piston for. cylinder I3 being .indicatedat. I 8 in Fig. 3, both piston l8 and the other piston: l9 appearing in Figs. 9, 1O and13;

Each .of the. reversing valve cylinders 5 and l 6 houses a reversing valve} thereversingvalve for cylinder I5 beingindicated'at zll in. Fig. 8, both reversing valve .zflrand the other reversing valve 2! appearing iii-Figs; Qand' 10. The reversing valve 29. reverses thedirection'oi movement of the pump piston l8 directly below it; While this reversing valve 29. is hydraulically-operated under control of the pump pistonv 19 in the other pump cylinder 12. .The pump piston l9 in pump cylinder I2 is reversed by the reversing valve 2! immediately above it in ,cylinder l5 and this reversing valve 2l is hydraulically operated under control of -.the other pump piston 18 in pump cylinder I3. I t v v f As indicated in. Fig 9, the pump cylinders l2, l3 may be cast in one ;blook, the reversing valve cylinders l5, IS in another block fitting" on top thereof and secured thereto by bolts such as indicated at 22. These two blocks form the casing 8.

Both of the pump pistons I8, I9 are alike in construction. As shown in Figs. 8 and 13, piston I8 has a piston head 24 and a piston head 25 at opposite ends of a tubular member 26, the latter being of smaller diameter than the piston heads 24, 25. Piston head 24 slides in a cylinder liner 2'! and piston head 25 slides in a cylinder liner 28. Between cylinder liners 21 and 28 is arranged a suitable packing gland 29 in which the member 26 slidingly fits. The outside diameter of the liners 21, 28 and the gland 29 are substantially the same and they fit in a bore 36 in the pump casing 8. The bore 36 and the outside of the liners 21, 28 have a number of opposed cored or cutaway portions to provide annular passages around the liners, as later described. The outer end of liner 21 has an annular array of cutaway portions such as indicated at 3| whereby the pressure or discharge of the working fluid in passage 32 may communicate with the outer end of piston head 24. Similarly the working pressure or exhaust in passage 33 is communicated to the outer end of piston head 25 through a suitable annular array of ports or openings 34 in the outer end of liner 28.

When piston I8, as shown in Fig. 8, is moving to the left, piston head 24 is on its suction stroke as the pumping space between the inner end of piston head 24 and the left side of gland 29 is increasing in size, and fluid of which the pressure is to be increased is admitted into this space from the annular passage 35 through an annular array of ports such as 36 in the inner end of liner 21. Similarly the space between the inner end of piston 25 and the right hand side of gland 29 is decreasing in size and the fluid previously admitted to that space is increased in pressure and pumped out through an annular array of ports such as 31 to the annular passage 38.

The ratio of the boost in pressure is substantially the same as the ratio of the area of the outer end of the piston heads such as 25, to the area determined by the diflerence in the area of piston head 25 and the area of the cylinder connecting member 26. With the relative dimensions shown in the drawings this ratio is of the order of five to one, although other ratios may be used.

A check valve unit is provided for each of the two pumping spaces which exist for each of the two pump pistons l8 and I9, and the four check valve units 46, 4|, 42, 43, a top view of which appears in Fig. 3, are arranged in pairs at opposite sides of the two pistons I8, I9 and at right angles thereto.

As shown in Fig. 13, check valve unit 46 handles the suction and high pressure outlet for the pump action produced by piston head 24, check valve unit 4| handles the flow pumped by piston head 25, check valve unit 42 handles the flow pumped by piston head 44 and check valve unit 43 handles the flow pumped by piston head 45. Referring to Fig. 9, the casing 8 has a through passage 46 ex-- tending at right angles to and above the pistons I8 and I9. Passage 46 communicates with the high pressure outlet 1 and it may have at one end thereof a plug 41 so that the outlet pipe may be connected to either end of passage 46 and the plug 41 secured at the other end. Also casing 8 has below pistons I8 and I9 and parallel to passage 46, a through passage 48 which communicates with the high pressure suction inlet 6. Passage 48 is likewise threaded at both ends and has a cap 49 at one end so that thiscap may close either end of passage 48. and the inlet connection made at the other end. Referring to Fig. 13, the check valve units 46 and. 42 extend on one side of the high pressure passages 46 and 48 and check valve units 4|, 43 extend on the other side of passages 46 and 48.

All four of the check valve units 46-43 are alike in construction and for example, as shown in Figs. 10 and 13, pump passage 38 on a suction stroke opens inlet check valve 50 and closes outlet check valve 5|, and when on a pumping or pressure stroke, closes check valve 56 and opens check valve 5| On a suction stroke the fluid flows past valve 56 through ports 52 in a cage 53 to the pumping space 38, and on a pressure stroke the fluid flows from passage 38 through openings 54 in cage 53, past valve 5| to outlet 1.

The check valve unit 4| is removably held in a bore 55 in casing 8, by a cap 58. Check valve 5| is held to its seat 59 by a spring 66 between cap 58 and valve 5|. Cap 58 at its inner end forms a cage having discharge openings 6| and the bore 55 is enlarged around those openings as indicated at 62. Cap 58 holds its cage on seat 59 which bears on the top of cage 53. Bore 55 is enlarged around openings 54 as indicated at 63. Cage 53 at its lower end has a stop 64 for valve 56 and spring 65 is arranged between stop 64 and valve 50 to hold the latter to its seat 66, the lower end of cage 53 bearing on the top of seat 66.

The suction or inlet end of all four of the inlet check valves like 56 are connected to the suction inlet 6 by reason of the fact that inlet passage 48 shown in Fig. 9 branches at its opposite ends, the branch passage for check valve units 46, 4| being indicated at 56 in Fig. 12. Similarly the discharge end of all four check valve units 46-43 feed into the high pressure outlet 1, by reason of the fact that the outlet passage 46 shown in Fig. 9 branches at its opposite ends, the branch passage for valve units 46 and 4| being indicated at 51 in Fig. 12.

The reversing valves 26 and 2| are similar in construction and in operation, although they operate out of phase and at diiTerent times, as later described. As shown in Fig. 8, reversing valve 26 has a hollow piston 16 at one end, a hollow piston H at the other end and an intermediate cylinder valve head 12, all of the same diameter and slidably fitting in a cylinder liner 73 held in cylinder I6 by heads 14 and 15, Head 14 has an inwardly projecting cylindrical portion 16 which extends in and forms a stop for the hollow piston H, and head 15 has a similar stop 11 for hollow piston 16. Liner 13 has seven annular arrays of ports and cylinder I6 has an annular cored passage for each such array, to wit, liner 13 has at its left end ports 18 which communicate with pipe 19 and at its right end ports 83 which communicate with pipe 84, to operate valve 26 by admitting pressure to the outer end of either piston 16, or II and connect the outer end of the other piston to exhaust. Port 86 is opened or closed by piston head 25 and is arranged in liner 28 at a point intermediate the travel of piston head 25. Port 66 communicates with an annular passage 8|, partly in liner 28 and. partly in casing 8, passage 8| being connected to pipe 82.

Pump piston 24 opens and closes a port 85 in liner 21, similar to port 86, at an intermediate point in its travel, port 85 communicating with an annular space 86, partly in liner 21, partly in casing 8, space 86 being connected to a pipe 81.

The length of piston I8 is such that both ports 86 and 85 are open at the same time, whereby the one of these ports which is on the pressure side aha-are of pum piston l8 o'p'ens completely hefor'the other port which is on the exhaust side begins to close, to shift reversing valve 21- toits'alt'ern 'e position, both reversing valves 26' and 2t being fast acting. The distance from port was the outer end of its liner 28 is the same" asth=;di's'-- tance from port 85t0' the outer end of liner 2'! and that distance is less than the lengt or piston heads 24 and 25, whereby when either of these ports is closed: by outward-'move'rrient'ofits piston 24 or 25 that port remains closed until the piston head reaches theend of'its stroke and returns to a position opening the port: The' same arrangement of ports like Strand: 85 are provided for the other pump piston t9, the port eer e: spending to 86' being reterre'd to as 80 and th'e port corresponding to 85 being referred to 85 The pump piston [8, by controlling ports 80, 85, acts as a pilot valve for the reversing valve trierthe other pump piston t9, and similarly pump. inclusivaisswungrearwardly 180 about avertical" piston H), by controlling ports=-80"; 85" sets as a pilot valve for reversing valve 20; However,- the connections from those ports tomeirresp: tive reversing valves is reversed for one of thos' reversing valves. Accordingly, port 85'at -the left end of piston I3 is connected by pipe 81 to-th' lft end of 21' (see Figs. 3', 8' and II) amt the port 80 at the right end of piston l'8 is eohnectedb3'f' pipe 82 to the right end of valve 21, Eliot/ever. the port 85' at the left end of piston l 9is connected by pipe 84 to the right end of vaw rmane port 80' at the right end of piston I'9 is connected" by-pipe T9 to the left eh'dof Valve 20?- 'Ijh' pur pose of this is to cause pump pistons F8 aud tswith a; crosswise cored passage l M showir in-iFigs. and "131 wherebi the working pressure fiuidin inlet 9" communicat'ed not only to the annular space 93- forr'eversing'valvem; but to the similar 6" annular space I02 and inlet ports 9 corresponding' to inlet ports 94in Fig. 8 for the other re versin'g valve 2 I; as shown in Fig. 11.

The operation of the booster above described,

will now be explained, Fig. 2 illustrates the The'operation will be further described in: connection with the schematic'drawings in Figs'.4'7,

whereinthe apparatus' is spread out; If the'right hand halfof each of the drawings in Figs. 4-7,

line-through the middlepf' each drawing; so that pump piston l9 will extend pa'rallelto and behind piston f8: and valve 2! similarly will ex= tend behind and parallel't'o valve 253, thespace 5s relation of the pistons and'valves in Figs: 4-7

0'; in mind thattheleft end of valve 21 and the left end" of piston lfiyasthey appear iIT'Fi gS; 4 7; are actually theright hand ends thereof" in the apparatus shown in the figures such as Figs: 3'; 81-3. Whilethe' space relation of pump pistons" to have overlapping strokes, each beiugactiveaerandreversing valves sh wn t pp when the other is idle, to reduce"pulsations-iii th high pressure output.

As shown in Fig. 9, pump" cylinders 1; and f3 may be spaced apart and pipes!!! and fl mav eii tend in the space between those cylinders Liner l3'has an annular arrayof porters-com: municating with anannula'r space89which leadsto the Working fluid outlet HJ; when reversing valve is in the position shown-in l ig". 8, ek

Figs. Rand 8 t0 13-is preferred; as the'various elements are associated in. a compact structure; a various other space relations may be employed:

In setting the booster into operation, if the pump pistons l8; l9" are not-initially outof phase With each other, they may bamoved toouIT-ofphase relation by temporarily admittingpressui'e to one end or the other of one of the pump p'i'stons; or one of the reversing valves over tem haust ports 3 en o ne e g a' 5-tporary fluidpressure lines, not shown;

the outer end of piston he'ad Manama-passage 32, through annular passage fi'll' and p'or '9 in liner [3, around reduced stem QRZ thioug haust ports 88 and space-sermons-theworking fluid outlet lo; I valve portion '12 admits the working pr ssure; at inlet 9 through annular space'9-3 tli'rough' inlet ports 94 in liner'13, around reduced st'exii through annular ports sfi in liner flfl and annul space 91 and passage iie f to-the right endor pi tonhead 25. Also at this tiniethe' hollow iii ton H closes the annular array f erase-steers 98 in liner 13, these ports comma-meeting wan an annular space 99 which is cenneetea mreagn with the working pressure outlet l0. As shown in Fig. 11, the exhaust passage mo also connects exhaust ports 88' and 9B" for reversing valve 2| corresponding to exhaust ports 88 a'nd- 58 0f re"- Hereafter, reference will be made to the right or left-end of the valves or pistons as they actually appear in Figs. 45-72 Referring'to Fig; 4,'the workingcpressure in inlet-4 as controlledby valve 2|," At this time; the intermediate 56 4s applied to the'right end o p p p sto 9 whichhas reached the end of its stroke andto' the right end of valve 2i! which has also'r'eache'd the end of its stroke;

ton lit has uncovered port 89 which eommuni-'-- sates the pressure on the right end of'piston' IS a longitudinal cored passagellill-"shbwii'in 11 66 to reversing valve" 2| which is fast acting and" as shown in Fig. 5,'-pist'oni8 completes itsstroke to-the-leftand in so doing maintains port 85 verging va1ve go to the workjng fegsuf'omlefi ofi closed whieh is of no consequence because'valve When reversing valve 20 is in its alternateposi: tion in Fig. 8. exhaust ports are closed piss ton Hi, the workingpressure ininlet e being in- 2l has-"already movedto'the end of itsstroke to'the'right, valve ZI'being-in po'sitionto' admitthe-workingpressure in pipe Wto-the left end ofpiston lfi'which-travelsto therightuntilit um municated to the left end ofpistou-headwaend 70* s port 8 at a t when p mis l the rightend of piston head' ZS' beihg connected through passage 33-a-nd exhaust-pens 98 arid-pan sage I00 to the working pressure outlet ID.

The annular passage 93 which communicates with the working pressure inlet 9 communicates 76 its stroke to the right.

open, thereby communicating the pressureon the left endof'pistom IS-tothe left en'd'ioi valve?! 1 which-is quick acting and moves to the" right-and remains there while piston 19 is completing Piston l9 moves from the The working pressure in inlet 4 as contrclled" by valve 25', is'app'lied'to' -5$' =the"right end' of piston I8 which is at an termecliate positioninits stroke and: traveling to the-1eft'." Atthemomentshown'in'Fig. 4; pis-* position shown in Fig. to the end of its stroke at the right as shown in Fig. 6, while piston l8 moves from the end of its stroke as shown in Fig. 5 to the position shown in Fig. 6. Piston l8 in the position shown in Fig. 6 uncovers both ports 85 and 80 thereby admitting the working pressure on the left end of piston l8 and on the right end of valve 2| which moves to its alternate position shown in Fig. 7. While piston I8 is completing its stroke to the right from a position shown in Fig. 6 to the end of its stroke shown in Fig. 7, piston l9 moves to the left to the position shown in Fig. 7 whereby the working pressure on the right end of piston is is communicated through port 85 to the right end of valve 20 which moves to its alternate position to the left. Pump piston l9 then completes its stroke to the left and piston l8 moves in the course of its travel to a position uncovering ports 85 and 80 which is the condition shown in Fig. 4. The cycle of operations above described is, of course, repeated and each of the pump pistons l8, l9 pump and boost the pressure on its stroke in each direction.

It will be apparent that various modifications may be made in the invention without departing from the spirit of the following claims.

I claim:

1. A hydraulic booster comprising a pair of fluid pressure operated differential double acting pump pistons each having two pump and two motor piston areas, a fluid pressure operated reversing valve for the motor piston areas of each of said pistons, and means for operating said pistons out of phase with each other whereby one piston is at an intermediate position in its stroke when the other piston is at either end of its stroke, said means comprising fluid pressure operated means actuated when each of said pistons is at an intermediate position in each stroke for actuating the reversing valve for the motor piston areas of the other piston.

2. A hydraulic booster comprising a pair of fluid pressure operated differential double actin pump pistons each having motor piston areas, a fluid pressure operated reversing valve for the motor piston areas of each of said pistons, and means comprising ports controlled by each of said pistons and passages between the ports of one piston and the reversing valve of the other piston whereby eachof said pistons acts as a pilot valve for the reversing valve of the other piston.

3. A hydraulic booster comprising a pair of fluid pressure operated differential double acting pump pistons each having motor piston areas, a fluid pressure operated reversing valve for the motor piston areas of each of said pistons, and means comprising fluid pressure and exhaust passages controlled by each of said pump pistons whereby each of said pump pistons serves as a pilot valve for the reversing valve for the other pump piston.

4. A hydraulic booster comprising a pair of fluid pressure operated differential double acting motor-pump piston members, a fluid pressure operated reversing valve for the motor side of each of said piston members, and means comprising ports controlled by the movement of each of said piston members for hydraulically operating the reversing valve for the other piston member.

5. A hydraulic booster comprising two pump cylinders, a fluid motor double acting pump piston for each of said cylinders, two valve cylinders,

a reversing valve for each of said valve cylinders, fluid passages whereby each of said valves is adapted to alternately connect the opposite ends of one of said pump cylinders with a fluid pressure inlet and an exhaust respectively, each of said pump cylinders having two ports adapted to be opened or closed by the piston in its travel, the said ports of each pump cylinder being spaced apart farther than the length of the piston whereby the port on the pressure side is fully open before the port on the exhaust side begins to close, and passages connecting the two ports of each pump cylinder to the opposite ends respec tively, of the valve cylinder for the other pump piston, each of said reversing valves being fast acting and said pump pistons having overlapping strokes.

6. A hydraulic booster comprising a pair of fluid pressure operated difierential double acting motor-pump piston members, hydraulic means for operating'said motor pump piston members with overlapping strokes, said means comprising a port intermediate each stroke of each of said piston members, a fluid pressure operated reversing valve for the motor side of each of said piston members, and means comprising passages controlled by the ports for each piston member for operating the reversing valve for the other piston member.

7. Hydraulic booster apparatus comprising a pump cylinder block having therein a pair of horizontal parallel pump cylinders extending side by side, a double differential pump piston in each of said cylinders, a reversing valve block on top of said first block, a pair of horizontal parallel reversing-valve cylinders in said valve block, a reversing valve in each of said valve cylinders for each of said pistons, two vertical check valve wells in said first block for each of said double pump pistons, a double check valve in each of said wells, said valve block having a working fluid pressure inlet passage and a working fluid pressure exhaust passage for both of said reversing valves, said valve block and said pump block having communicating passages connecting both ends of each piston with one of said valves, said pump block having a high pressure suction passage and a high pressure outlet passage communicating with all four of said check valve wells, said pump block having a pair of pump passages for each piston, each pump passage communicating with one of said check valve wells, and means for operating each of said reversing valves under control of one of said pump pistons.

8. A hydraulic booster according to claim 2 comprising a block forboth of said pistons, a valve block for both of said reversing valves, said valve block having an inlet and an exhaust, said blocks fitting together and having communicating passages controlled by said valves and connecting said inlet and exhaust with said pistons.

J. D. BUCHANAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 323,346 Leavitt July 28, 1885 1,161,787 Nichol Nov. 23, 1915 2,293,076 Ponting Aug. 18, 1942 2,336,446 Tucker, et al Dec. 7, 1943 

